"use client";

import { useState, useEffect } from "react";

export const ThemeToggle = () => {
  const [isDark, setIsDark] = useState(false);

  useEffect(() => {
    // 检查本地存储或系统偏好
    const stored = localStorage.getItem("theme");
    const prefersDark = window.matchMedia("(prefers-color-scheme: dark)").matches;
    
    const shouldBeDark = stored === "dark" || (!stored && prefersDark);
    setIsDark(shouldBeDark);
    
    // 应用主题
    if (shouldBeDark) {
      document.documentElement.classList.add("dark");
    } else {
      document.documentElement.classList.remove("dark");
    }
  }, []);

  const toggleTheme = () => {
    const newTheme = !isDark;
    setIsDark(newTheme);
    
    if (newTheme) {
      document.documentElement.classList.add("dark");
      localStorage.setItem("theme", "dark");
    } else {
      document.documentElement.classList.remove("dark");
      localStorage.setItem("theme", "light");
    }
  };

  return (
    <button 
      onClick={toggleTheme}
      className="flex items-center justify-center w-10 h-10 rounded-xl bg-gray-100 hover:bg-gray-200 dark:bg-gray-800 dark:hover:bg-gray-700 transition-colors"
      aria-label="Toggle theme"
    >
      {isDark ? (
        // 太阳图标 (浅色模式)
        <svg className="h-5 w-5 text-gray-600 dark:text-gray-400" fill="none" stroke="currentColor" viewBox="0 0 24 24">
          <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M12 3v1m0 16v1m9-9h-1M4 12H3m15.364 6.364l-.707-.707M6.343 6.343l-.707-.707m12.728 0l-.707.707M6.343 17.657l-.707.707M16 12a4 4 0 11-8 0 4 4 0 018 0z" />
        </svg>
      ) : (
        // 月亮图标 (深色模式)
        <svg className="h-5 w-5 text-gray-600 dark:text-gray-400" fill="none" stroke="currentColor" viewBox="0 0 24 24">
          <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M20.354 15.354A9 9 0 018.646 3.646 9.003 9.003 0 0012 21a9.003 9.003 0 008.354-5.646z" />
        </svg>
      )}
    </button>
  );
};